Sensing Intra‐ and Extra‐Cellular Ca²⁺ in the Islet of Langerhans

Abstract

Calcium ions (Ca2+) take part in intra‐ and inter‐cellular signaling to mediate cellular functions. Sensing this ubiquitous messenger is instrumental in disentangling the specific functions of cellular sub‐compartments and/or intercellular communications. In this review, the authors first describe intra‐ and inter‐cellular Ca2+ signaling in relation to insulin secretion from the pancreatic islets, and then outline the development of diverse sensors, for example, chemically synthesized indicators, genetically encoded proteins, and ion‐selective microelectrodes, for intra‐ and extra‐cellular sensing of Ca2+. Particular emphasis is placed on emerging approaches in this field, such as low‐affinity Ca2+ indicators and unique Ca2+‐responsive composite materials. The authors conclude by remarking on the challenges and opportunities for further developments in this field, which may facilitate a more comprehensive understanding of Ca2+ signaling within and outside the islets, and its relevance in health and disease.

Self-assembly of microstructured protein coatings with programmable functionality for fluorescent biosensors

“…The ΔF/F 0 was also plotted against the concentrations of Ca 2+ in the millimolar level that falls within the calcium levels in the extracellular matrix, from 0.5 to 3.0 mM (Figure 4D). [49–51] At this Ca 2+ concentration level, we observed a drastic change in the fluorescence that was linearly dependent on the concentration of Ca 2+ . The measured ΔF/F 0 was from 76% to 223% at the Ca 2+ concentrations of 0.5 to 5.0 mM, respectively, and an equilibrium binding model did not provide a good fit to the data.…”